Poly/Mono mode

[BobanSpasic]

Hi.
Could someone, please, implement the Mono play mode?
The settings should go under the Performance menu (like on DX7).

[probonopd]

Hello @BobanSpasic.

Looks like @dcoredump has implemented Mono mode in https://codeberg.org/dcoredump/Synth_Dexed/:

void setMonoMode(bool mode);
bool getMonoMode(void);

So we would "just" need to add a menu option for it, and save it in performance.ini.

Perhaps @arsamus could have a look at it?